Owing to the structural and functional complexity and relative inaccessibility of the central nervous system (CNS), most chronic neurologic and neurodegenerative disorders lack effective treatments, and, therefore, require the development of novel therapeutic approaches including gene therapy and cellular therapy. Krabbe disease, or globoid cell leukodystrophy (GLD), is an inherited, recessive disorder affecting the peripheral nervous system (PNS) and the CNS caused by defects of the lysosomal enzyme galactocerebrosidase (GALC). This enzyme catalyzes the lysosomal hydrolysis of galactosylceramide and galactosylsphingosine (psychosine). The enzyme defect causes a series of pathological changes including demyelination. This autosomal recessive disease affects humans and animals including dogs, mice, and rhesus monkeys. The goal of the proposed project is to explore gene therapy strategies for Krabbe disease using improved lentivirus-based gene and protein delivery strategies. These strategies will initially be tested in rats and later on extended to mice and rhesus monkeys affected with GLD. The Specific Aims are: 1. To modify HIV-l-based lentiviral vectors for improved transgene delivery and expression in the CNS. These vectors will harbor constitutive as well as regulatable promoters. Vectors will be pseudotyped with the vesicular stomatitis virus (VSV)-G glycoprotein. Pseudotypes involving the Mokola virus G glycoprotein will also be tested with a view toward distributing such vectors more globally in the CNS. Vector delivery will be carried out by direct brain injection. 2. To investigate protein transduction mechanisms with a view toward facilitating the global delivery in the CNS of GALC tagged with the transduction domain of HIV-1 TAT, the membrane translocating hydrophobic sequence from fibroblast growth factor or the herpes simplex virus VP22 protein. 3. To use lentiviral vectors to transfer the GALC cDNA into the brains of mice and rhesus monkeys affected with GLD to evaluate the capacity of such vectors to correct the GLD defect and histological abnormalities.